Attachment plug



Oct. 27, 1959 w. P. CARPENTER ATTACHMENT PLUG 2 Sheets-Sheet 1 Filed May 25, 1956 INVENTOR. Wiilaam I? flair 0645a" BY W M M ATTORNEYS 2 Sheets-Sheet 2 1N VEN TOR.

ATTORNEYS W. P. CARPENTER ATTACHMENT" PLUG II/I \\Y\\\\\\\\\\\\\\\\\ 17 William P. ('a/ vexzzer W AR 1 \Q A 1 M W 7 l M M Q M F Oct. 27, 1959 Filed May 25, 1956 United States Patent ATTACHMENT PLUG William P. Carpenter, Bristol, Conu., assignor to The Superior Electric Co., Bristol, Cnn., a corporation of Connecticut Application May 25, 1956, Serial No. 587,331

Claims. (Cl. 317-14) The present invention relates generally to electric receptacles or connectors and more particularly to an improved attachment plug, usable in conjunction with standard household outlets and a variable voltage unit, which incorporates a protective device therein.

The present application is a continuation-in-part of my copending application Serial No. 542,380, filed October 24, 1955, entitled Remote Electrical Control, now Patent No. 2,840,765, granted June 24, 1958.

In the copending application, there is disclosed a variable voltage device which is plugged into a standard household outlet and has sockets for receiving the plugs of appliances, lighting fixtures, etc. The device is utilized to control the voltage to the appliance and, preferably, to regulate the luminosity of incandescent lamps which may be plugged therein.

An object of the present invention is to provide an improved combined plug and receptacle having control leads connected to the conductors of the device.

It is an object of the present invention to provide an attachment plug utilizable with a variable voltage unit in which the voltage unit is protected against an overload or a short circuit in the appliances or lighting fixtures controlled thereby.

It is another object of the present invention to provide an attachment plug which may be plugged into an ordinary wall socket and which has a plurality of sockets or receptacles so that more than one fixture may be connected thereto, and in which a single device protects against the total electric power passing through the plug.

It is a further object of the instant invention to provide an attachment plug of the above type which is capable of employing a standard type of electrical fuse and in which the fuse may be very readily replaced in the plug whenever necessary.

It is still a further object of the present invention to provide an item of this class which is adapted to modern manufacturing methods, is economical to fabricate, has relatively few parts and has a sightly appearance.

A feature of the present invention resides in providing an attachment plug which can be plugged into a household outlet and which has integrally formed therein, a plurality of sockets for receiving the male connectors of appliances and/or lamps. The plug is utilized with a variable voltage unit preferably an autotransformer and is provided with clips for engagement with a fuse to protect the unit from being overloaded. The fuse is positioned in one line of the output of the variable autotransformer and is responsive to the total current pass ing through the autotransforrner. In addition, the parts are arranged such that a fuse, upon being blown, can be easily replaced, even by a person totally unaccustomed to electrical repairs.

Other features and advantages will hereinafter appear.

In the accompanying drawing:

Figure l is a perspective of the attachment plug of the instant invention.

Fig. 2 is a longitudinal section thereof.

Patented Oct. 27, 1959 ice of the plug.

Fig. 7 is a schematic electrical diagram of the instant invention when utilized with a variable voltage unit.

Fig. 8 is a section of another embodiment of the attachment plug.

Fig. 9 is a section taken on the line 9-9 of Fig. 8.

Fig. 10 is a perspective of the electrical components of the embodiment shown in Fig. 8.

Fig. 11 is an end view of the plug.

Referring to the drawing, the attachment plug is generally indicated by the reference numeral 10 and has a housing preferably formed from a moldable insulating material, such as a plastic, Bakelite, etc., and is composed of two substantially symmetrical sections 11 and 12. Spun-over rivets 13 and 14 are employed to mechanically unite the sections. As shown in Figs. 1 and 6, parallel male prongs 15 and 16 extend from the housing and are adapted to be inserted in a standard female household outlet or socket (not shown). There is additionally, a three-wire conductor 17 having wires 17a, 17b and extending from the housing. The wires 17a and 17b are preferably connected to the input of a variable voltage unit such as the primary winding of an autotransformer, while the wire 170 is connectible to one line of the output of the unit, which may be the adjustable tap of the autotransformer.

As shown in Fig. 6, the prong 15 is connected to the wire 17a, While the wire 17b is connected to the prong 16 in order that the household voltage may be impressed across the winding of the autotransformer. A stepped element 18 is fastened to the prong 16 and is riveted as at 19, or otherwise secured to a resilient outlet bar 20. The bar 20 has bent-over end portions 21, and each end forms one side of the two outlets or sockets of the plug. The other side is formed by a similar bar 22 having bent-over portions 23 aligned with the bar 20 but displaced therefrom. An angle 24, preferably formed from electrical conducting sheet metal, is secured to the intermediate portion of the bar 23 as by rivet 25, though spot welding may be utilized if desired, and carries a resilient cartridge fuse clip 26. Another clip 27 is fastened to or may be formed integrally with an angular support member 28 which has secured thereto the end of the lead 170 as by soldering, as indicated by the reference numeral 29.

From the foregoing, when the prongs 15 and 16 are inserted into an electrical receptacle, such as is commonly found in offices or households and the wires 17a and 17b are connected across the winding of a variable autotransformer, with the wire 170 connected to the variable tap thereof, the autotransformer is utilized to control the voltage existing between the outlet bars 20 and 22. For example, if the bars 20 and 22 are in contact with the prongs of a male plug connected to an incandescent lighting fixture, such as table lamp or floor lamp, the brilliancy of the bulb can be controlled by the variable autotransformer to vary the amount of light emanating therefrom.

In the sectional views 2, 3, 4, and 5 of the completed plug, the prongs 15 and 16 are secured to the housing by means of rivets 30 and 31. each have an enlarged portion as indicated by the reference numeral 32, which is preferably imbedded in the sections 11 and 12 respectively during the molding operation forming the sections. The rivet 30 moreover, struc These rivets v arrangement of the various parts.

turally as well as electrically, connects the stepped element 18 to the prong 16. If desired, a clip 33 may be secured to the prong 15 by rivet 31 to facilitate electrically connecting the lead- 17a to the prong 15. The sections 11 and 12 are molded so as to provide openings 34 through which the prongs-15 and 16 may extend out of the housing and, additionally, are shaped to provide rectangular channels 35, one in each section, for maintaining the prongs rigid with respect to the housing 10. Each section 11 and 12 is molded to also provide four receptacles or male plug receiving slots 36, two of which constitute a socket, and thereis thus formed a socket at each end of the housing. The bar 22 is positioned within a rectangular channel 38 and the ends of the bent-over portions 23 are biased against a side 37a of a molded wall 37 so that when a prong of a plug is inserted through an opening 36 it resiliently engages the bent-over portion 23. The other bar 20 is likewise positioned within a channel 39 and its bent-over portions 21 are biased against the other side 37a of the wall 37 in order to resiliently engage a prong inserted therein.

As shown in Figs. 3, 4 and 5, the portion of the plug remote from the prongs and 16 is provided with a through aperture 40. The aperture 40 has an enlarged intermediate space 41 in which the two resilient cartridge fuse clips 26 and 27 are positioned. The clip 26 is maintained in position by reason of its attachment to the angle 24 while the clip 27 and the member 28 are held by a rivet 42 molded into the upper portion of the section 11 in a wall 43 defining the space 41. The rivet 42 is similar to rivets 30 and 31 and its head portion passes through an opening 44 formed in the member 28 and then the portion may be spun over to secure the clip 27 to the section 11.

The attachment plug of the present invention by having two sockets positioned on either side and by having a male prong adapted to enter a household socket, is capable of transmitting current therethrough which would normally be limited by the size of the appliances or lighting fixtures plugged into the sockets 36 or by a remote fuse in the household socket line. However, through ignorance or accident, if a lighting fixture or appliances needing a large electric current is plugged into the plug, the current therethrough may exceed the value at which the autotransformer is normally rated. Such condition may result in creating a fire hazard or in burning out the autotransformer.

To protect against such occurrences, a fuse 45 is inserted between one line of the autotransformer and the outlet sockets. Such a fuse is preferably a cartridge type of the kind normally used in automobiles, etc., and is positioned with its conducting portions in engagement with the clips 26 and 27. The clips moreover, resiliently engage the fuse and hold it in position.

The line 170 is connected to the variable tap of an autotransformer and forms one line in the outlets of the plug and accordingly, is electrically connected to the member 28, the clip 27, the fuse 45, the clip 26, angle 24 and the bar 22. Thus, for example, when two lighting fixtures are connected to the plug, one in each socket at the ends of the plug, the total current passing into both fixtures passes through the fuse 45 and thus, the autotransformer is protected for the total value of current flowing therethrough. Moreover, if no fuse is present then no current can flow through the plug and variable voltage unit.

When through mishap, too much current flows through the fuse 45 and it blows, the replacement of any fuse is exceedingly simple by reason of the construction and To remove a blown fuse, an instrument such as a screwdriver, may be inserted into the aperture 40 against one end of the fuse, after disconnecting the plug from the household socket,

and by merely pushing, the fuse 45 will be forced out the other end of the aperture 40 and can be removed and discarded. The tool is withdrawn and a new fuse is pushed into the aperture 40 until the clips 26 and 27 engage the conducting portions of the fuse. It should be noted that the clips 26 and 27 have their outer edges beveled as at 46 to facilitate the fuse exchange.

Shown in Fig. 7 is a schematic diagram showing how the attachment plug of the present invention may be used in conjunction with an adjustable autotransformer and two lighting fixtures to control the luminosity of the fixtures.

Two incandescent bulbs 46 and Y47 are shown connected to the outlet bars 20 and 22 as would occur when their male plugs are inserted into the openings 36. The wires 17a and 17b are connected to the prongs 16 and 15 respectively, and when the latter are inserted into a household socket, the voltage therein; is impressed across a winding 48 of an autotransformer 49. An adjustable tap 50 of the variable autotransformer 49 is connected to the line 17c, and, shown schematically, the fuse 45 is placed in series in this line. Accordingly, manipulation of the tap 50 is capable of controlling the total brilliancy of the bulbs 46 and 47 in the limits below that set by the protective device 45.

Shown in Figs. 8-11 inclusive is an attachment plug which may be utilized when it is desired to have the protective means not positioned within the plug. This embodiment is substantially like the attachment plug shown in Figs. 16 inclusive and described heretofore, and thus like reference numerals are used to indicate similar parts. Since, in this embodiment, it is preferred to have the protective device located remote from the plug, the output lead from the tap of the variable autotransformer 49 is connected directly to the bar 22, as by soldering indicated by the reference numeral 55, rather than through fuse clips. In addition, an angle 56 rather than a stepped connector is used to connect the prong 16 to the output bar 20. The housing sections 11 and 12 are formed with a slot 57 in the side of the housing opposite the prongs 15 and 16 and the leads 17a, 17b and 170 project therethrough. Moreover the aperture 40 of the previous embodiment is eliminated and the shape of the space 41 has been slightly altered so that it can accommodate the bent end portions of the leads.

From the foregoing, there has been disclosed an attachment plug which is used with a variable voltage unit for protecting against overloads in a variable voltage unit.

The plug is preferably formed with two symmetrical portions formed of dielectric, insulating material capable of being molded to form an economical, sightly device. The plug is provided with prongs for insertion into a standard household outlet and has two sockets for receiving the male attachment plug of conventional appliances and lighting fixtures. The number of parts in the plug is small in comparison to the results obtained and in addition, by reason of the novel arrangement of the elements, the replacement of a fuse can be carried out simply and readily.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

I claim:

1. An attachment plug for use with a variable voltage unit and for detachable connection to a household socket comprising a housing formed of insulating material and having a pair of projecting, spaced prongs adapted to enter the household socket; socket forming means positioned within the housing and having spaced members adapted for engagement with a male plug of a fixture when the fixture is connected to the attachment plug; a lead connected to each prong with both leads extending out of the housing and adapted to be connected to the input of the variable voltage unit; fuse containing means within the housing; and a lead connected to a portion of the fuse containing means extending outside the housing and adapted to be connected to the output of the variable voltage unit whereby a fuse may be inserted in the'fuse containing means contained within the plug to protect the variable voltage unit from being overloaded.

2. The invention as defined in claim 1 in which the fuse containing means comprises a pair of spaced, aligned clips and in which the housing has an aperture formed therein aligned with the clips whereby a fuse may be inserted into the aperture and into engagement with the clips.

3. An attachment plug for use with a variable voltage unit and adapted to be detachably connected to a household socket and have attached thereto a plug of an electrical appliance whereby the voltage unit can control the voltage to the appliance; comprising a housing formed of insulating material with a first pair of aligned, spaced channels; a pair of prongs positioned therein to extend therefrom and be adapted to enter a household socket; a second pair of aligned spaced channels formed in the housing and extending across the first pair of channels; wall means formed in the housing between the second pair of channels; a pair of bars, each one positioned in one of the second pair of channels; a connector connecting one prong to a first bar; a pair of fuse clips with a first fuse clip connected to the other bar and a second fuse clip mounted in the housing in spaced, aligned relation to the first clip; said second clip being insulated from the bars, prongs and first clip; in which the housing is formed with an aperture having its axis aligned with the fuse clips whereby a fuse may be inserted into the aperture to be engaged by the fuse clips, in which the second pair of channels extends through the housing to form on each end thereof a socket for receiving the male plug of a fixture, and in which the aperture formed in the housing extends through the housing and is substantially parallel with the second pair of channels.

4. A connector having a body formed from insulating material, a pair of spaced contact prongs secured in said body and having a portion thereof extending outside one face of said body for entry into a plug receptacle, a pair of spaced contact bars in said body extending transversely of said prongs and forming with the body a socket for lead connected to the second of said conducting bars.

5. A remote electrical control comprising a connector having a body formed from insulating material, a pair of spaced contact prongs secured in said body and having a portion thereof extending outside one face of said body for entry into a plug receptacle, a pair of spaced parallel contact bars in said body extending transversely of said prongs and forming with the body a socket for receiving an attachment plug, each of said prongs and bars being maintained in spaced, non-conducting relation by the body member, a conductor electrically connecting one of said prongs to a first of said conducting bars, a pair of fuse clips in said housing, an element connecting the other of the contact bars to one fuse clip, said housing being formed with an aperture aligned with the fuse clips whereby a fuse may be inserted into the aperture and into engagement with the clips, three leads extending from said body member, one end of a lead connected to each prong, and the end of the third lead connected to the second fuse clip, an autotransformer having a coil and a movable contact selectively positionable about the coil, the leads connected to the prongs being connected to the ends of the coil and the third lead connected to the movable contact.

References Cited in the file of this patent UNITED STATES PATENTS 1,748,838 Grier Feb. 25, 1930 2,072,389 Stayton Mar. 2 1937 2,137,593 Skojec Nov. 22, 1938 2,141,563 Skojec Dec. 27, 1938 2,480,827 Armstrong Sept. 6, 1949 2,484,092 Hopgood Oct. 11, 1949 2,636,096 DiBlasi Apr. 21, 1953 2,742,593 Voss Apr. 17, 1956 

